Ethylene from ethane halogen and hydrogen halide through fluidized catalyst

ABSTRACT

PROCESS FOR THE PREPARATION OF VINYL HALIDE BY OXYDEHYDROGENATION OF ETHANE TO ETHYLENE WITH A HYDROGEN HALIDE, HALOGEN AND OXYGEN FEED, OXYHALOGENATION OF THE ETHYLENE TO 1,2 - DIHALOETHANE, DEHYDROHALOGENATION OF THE 1,2-DIHALOETHANE TO VINYL HALIDE, AND RECYCLE OF PART OR ALL OF THE HYDROGEN HALIDE FROM THE PRODUCTION OF VINYL HALIDE TO THE OXYDEHYDROGENATION STEP. A PREFERRED CATALYST FOR THE OXYDEHYDROGENATION STEP INCLUDES A LOW CONCENTRATION OF COPPER OR IRON HALIDE WITH REAR EARTH HALIDE, THE RATIO OF REAR EARTH HALIDE TO COPPER OR IRON HALIDE BEING GREATER THAN 1:1. OTHER PREFERRED CATALYST COMPONENTS INCLUDE ALKALI METAL HALIDE AND MANGANESE HALIDE.

April 25, 1972 w R JR 3,658,933

ETHYLENE FROM ETHANE HALOGEN AND HYDROGEN HALIDE THROUGH FLUIDIZED CATALYST Filed July 14, 1969 ETHANE OXYGEN-- ETHANE OXYDEHYDROGENATION HALOGEN ETHYLENE OXYGEN-- OXYHALOGENATION DIHALOETHANE HYDROGEN DEHYDROHALOGENATION a DE VINYL HALIDE U.S. Cl. 260-6833 16 Claims ABSTRACT OF THE DISCLOSURE Process for the preparation of vinyl halide by oxydehydrogenation of ethane to ethylene with a hydrogen halide, halogen and oxygen feed, oxyhalogenation of the ethylene to 1,2 dihaloethane, dehydrohalogenation of the 1,2-dihaloethane to vinyl halide, and recycle of part or all of the hydrogen halide from the production of vinyl halide to the oxydehydrogenation step. A preferred catalyst for the oxydehydrogenation step includes a low concentration of copper or iron halide with rare earth halide. the ratio of rear earth halide to copper or iron halide being greater than 1:1. Other preferred catalyst components include alkali metal halide and manganese halide.

BACKGROUND OF THE INVENTION The present integrated process for the production of vinyl halide beings with the production of ethylene. Unsaturated hydrocarbons such as ethylene are commonly produced by either thermal cracking or catalytic cracking or a combination of both. In the known processes the principal disadvantage is low conversion of the saturated hydrocarbon to unsaturated hydrocarbon. In the literature, the reported conversion is rarely greater than about 40 percent. See, for instance, US. Pat. 3,119,883, US. Pat. 2,971,995 and British Pat. 969,416. It will be seen that product streams containing less than 30 percent of ethylene are not uncommon. In addition to low hydrocarbon conversion, the prior art processes often result in a product containing a variety of materials which are difiicult to separate. For instance, in the case where ethane is the feed material, substantial quantities of acetylene and methane are often produced. When ethylene is the desired product, serious problems are encountered due to the difficulty of separating these materials. Also, when a catalyst is employed in the known processes, experience has shown that periodic shutdown is necessary due to the fouling of the catalyst with tars and resins. Also, in many cracking operations exceedingly high temperatures are often necessary, e.g. see US. Pat. 3,119,883.

A primary purpose of the present invention is the provision of a step-wise process for the production of vinyl halide beginning with the oxydehydrogenation of ethane to ethylene and proceeding through the oxyhalogenation of the ethylene to 1,2-dihaloethane and the dehydrohalogenation of the 1,2-dihaloethane to vinyl halide so that economies may be effected by recycling the hydrogen halide produced in the vinyl halide step back to the oxydehydrogenation step.

Another primary purpose of this invention is to provide a process for the oxydehydrogenation of ethane to produce ethylene wherein the conversion of ethane to ethylene is substantially increased. Other purposes are the provision of (1) a continuous oxydehydrogenation process wherein shutdown due to catalyst fouling is avoided, and (2) an oxydehydrogenation process which does not require excessively high temperatures.

"United States Patent O ice 3,658,933 Patented Apr. 25, 1972 SUMMARY OF THE INVENTION The present invention provides a process for the oxydehydrogenation of ethane to ethylene in the presence of hydrogen halide, the improvement comprising employing a halogen with said hydrogen halide.

The invention also provides a process for the preparation of vinyl halide by cracking dihaloethane which has been prepared by oxyhalogenating ethylene which has been prepared by oxydehydrogenating ethane in the presence of a hydrogen halide and a halogen, the improvement comprising recycling at least part of the hydrogen halide produced in the cracking to the oxydehydrogenation.

In addition the invention provides a supported catalyst for the production of ethylene by the oxydehydrogenation of ethane in the presence of hydrogen halide, halogen, and oxygen which comprises, in combination, from about 0.15 weight percent to about 3 weight percent of a metal halide selected from the group consisting of copper halide and iron halide, the weight percent being based on the total weight of said supported catalyst, and rare earth halide, the weight ratio of said rare earth halide to said metal halide being in excess of 1:1.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows a block diagram of the flow scheme of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The above and other purposes are accomplished stepwise, first by a process for the oxydehydrogenation of ethane to ethylene by contacting ethane with a fluidized catalyst, hydrogen halide, halogen, and oxygen, the oxygen usually being in the form of air, at a temperature above 350 C., or more preferably from about 400 C. to about 650 C., and a pressure above atmospheric, or more preferably from about one atmosphere to about 30 atmospheres, the fluidized catalyst being composed of a mixture containing essentially from about 0.15 percent to about 3.0 percent copper or iron halide and from about 5 percent to about 20 percent rare earth halides (hydrated) supported on a fluidized carrier, the percentages being based on the total weight of catalyst and support. The weight percent of the rare earth halides as set forth-herein is based on the hydrated form, although such halides need not be hydrated during use.

In the oxydehydrogenation reaction ethane is converted to ethylene in yields as high or higher than 60 percent, and even as high as, for example, 86 percent, without the occurrence of catalyst fouling or the necessity of the excessive temperatures normally associated with cracking operations. Furthermore, this method is economical in its internal recycle of hydrogen chloride, which was at one time a troublesome byproduct in the petrochemical industry and often disposed of by dumping into pits containing oyster shells, but is now in short supply and strong demand. Moreover, this process utilizes ethane, an abundant and inexpensive hydrocarbon, as a raw material for conversion into the more valuable chemical, ethylene.

The primary reason for the improved results of the oxydehydrogenation step is the use of a fluidized, supported mixture of copper or iron halide and rare earth halides. In all instances the ratio of rare earth halides (hydrated) to copper or iron halide must exceed 1:1 and should very preferably fall within the ranges hereinafter specified. Preferred conditions are (in weight percent based on the total amount of catalyst and support) a catalyst mixture supported on a fluidized solid carrier containing essentially from 0.15 to about 3.0 percent copper aesagss or iron halide and from about percent to about 20 percent rare earth halides (hydrated). Preferably, the catalyst mixture contains from about 0.25 percent to about 0.35 percent copper halide or from about 0.3 percent to about 0.4 percent iron halide and from about 8 to about 15 percent rare earth halides (hydrated). When the amount of rare earth halide and copper or iron halide in the catalyst significantly deviates from that specified above, ethylene is not usually produced and, if produced at all, is produced in only small quantities. Instead, halogenated hydrocarbons are produced as the major product. This very significant relationship between the amount of copper or iron halide and rare earth halides will be illustrated by the examples set forth below.

By the term rare earth halides is meant the halides of the elements in the lanthanum series, that is, elements having an atomic number of from 57 through 71, and mixtures of these compounds. Included among the rare earth elements are thulium, lanthanum, cerium, praseodymium, neodymium, prometheum, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, ytterbium, lutecium, yttrium. Among the elements cerium is preferred, but praseodymium and neodymium are also excellent catalyst components for the present process. However, since these materials are usually found in nature in mixtures, it is very convenient to use a commercially available mixture. The mixtures used in formulating the catalyst contain rare earth halides, preferably chlorides, or oxides or other mixtures. Examples of minerals containing the rare earths are zircon, thorite, monazite, gadolinite, cerite, orthite, and the like. The mixture known in the art as didymium is suitable, but the mixture extracted from monazite without removal of cerium and thorium is preferred.

The temperature of this process should be above 350 C. and should preferably range from about 400 C. to about 650 C. and more preferably from about 475 C. to about 600 C. It is desirable that the pressure range from about 1 atmosphere to about 30 atmospheres and preferably from about 1 atmosphere to about 20 atmospheres. The oxygen used in this invention is usually used in the form of air; however, pure oxygen may be employed if desired.

The fluidized support may be any of the known inert carriers such as sand, diatomaceous earth, alumina, silica gel, pumice, bauxite, chromia-alumina, and the like. Preferably the catalyst support is chromia-alumina, but alumina and silica are highly satisfactory. It is highly preferable that the particle size of the impregnated catalyst be Within the range of from about 120 mesh to about 325 mesh (U.S. Sieve No.). In other words, the preponderance of the catalytic material be no coarser than about 120 mesh and no finer than about 325 mesh. There is no necessity that all particles be of uniform size. The size distribution generally varies throughout the ranges indicated. Usually it is preferred that not more than about 90 percent of the catalyst be finer than 325 mesh and that not more than about 50 percent of the catalyst be coarser than 120 mesh.

If desired, an alkali metal halide may be added to the catalyst mixture in a concentration of from about 0.01 percent by weight to about 5 percent by weight, based on the total weight of catalyst and support. Preferably, it is added in concentrations of about 0.05 percent to about 3 percent, and more preferably from about 0.1 to about 2 percent. The alkali metal halides employed are preferably the chlorides of lithium, sodium, potassium, rubidium and cesium. The addition of alkali metal halide to the catalyst mixture is a preferred embodiment of the invention, and among the alkali metal halides, lithium halide is most preferred.

Other catalyst additives also enhance the performance of the catalyst of this invention. Among such additives, manganese halide in a concentration of from about 1 to about 10 percent by weight, based on the total \weight of catalyst and support, is preferred. Other suitable catalyst additives include zinc halide, calcium halide, and titanium halide, among which calcium halide is preferred in a concentration of from about 1 to about 10 percent by weight, based on the total weight of catalyst and support.

The addition of iron halide to the copper halide containing catalyst, or vice versa, has also been found beneficial, depending upon the type and quantity of other components in the catalyst. A concentration of from about 1 to about 10 weight percent of the copper or iron halide added, based on the total weight of catalyst and support, is preferred.

Another important feature of the invention is the molar feed ratio ethane/hydrogen halide/air/halogen which varies in the ranges l/0.5 to 2/ 0.5 to 5/01 to 1. When oxygen is substituted for air, the ratio varies in the ranges l/O.5 to 2/0.l to l/0.l to l; the stoichiometric feed ratio is l/l/0.25/0.5. A diluent such as nitrogen, carbon dioxide, or helium may be added to the preceding ratios in a range of 0.25 to 2.

The rate of flow gases through the reaction zone is subject to some variation. Thus, sufiicient flow of gases must be provided for fluidization of the supported catalyst. On the other hand, gas flow should not be so extreme as to blow sifim'ficant quantities of the catalyst out of the reaction zone. It is generally preferable that the superficial linear velocity of the gases entering the reactor be maintained within a range of from about 0.1 to about 5 feet per second. More preferably, for reasons of economy, the superficial linear velocity is maintained from about 0.5 foot per second to about 3.5 feet per second. A suitable contact time is one ranging from about 1 second up to about 20 seconds, and preferably, for best conversion, the contact time should be from about 2 to about 15 seconds.

The feed ethane, oxygen (which may be pure, in the form of air or mixed with inert diluents), halogen, and hydrogen halide may be fed together into the bottom of the reactor. This can be varied however and it is indeed often desirable to do so. For instance, one or some of the reactants may be fed into one portion of the reaction zone and the other or rest of the reactants into another portion.

As shown in the flow scheme depicted in the drawing, the above described ethane oxydehydrogenation is the first of a three-step process for producing vinyl halide. A principal advantage of this process resides in the recycle of part or all of the hydrogen halide from the last step to the first. Thus, at 100 percent elliciency the halogen added in the first step would all be removed as a part of vinyl halide in the third step, and the hydrogen halide would be continuously recycled without depletion. However, as a practical matter it is found that some hydrogen halide must be added to the process from external sources.

While the ethane oxydehydrogenation process above described preferably employs a unique process, conventional processes known in the art are suitable for the oxyhalogenation and dehydrohalogenation steps. However, according to a preferred embodiment a mixture of from about 1 to about 50 weight percent ethane, from about 40 to about 95 percent ethylene, and from about 20 to about 40 weight percent hydrogen chloride is passed from the ethane oxydehydrogenation step to the oxyhalogenatio-n step. Oxygen (pure or as air) is added in the oxyhalogenation step which is conducted at from about to about 250 p.s.i.g. and at from about 2-00 to about 400 C. The reactants are passed through a supported metal halide catalyst which is maintained in a fluidized state by a reactant flow rate of from about 0.2 to about 2 feet per second at reaction temperature. Contact time is maintained between about 1 and about 20 seconds. Operating under these conditions, from about to about 99 percent conversion of ethylene to 1,2-dihaloethane is achieved. I

Also according to a preferred embodiment, the mixture from the oxyhalogenation step which includes from about 50 to about 90 percent 1,2-dihaloethane, from about 1 to about 20 weight percent ethane, and from about to about weight percent hydrogen halide is passed to the dehydrohalogenation step. The dehydrohalogenation is conducted at from about 400 to about 600 C. and from atmospheric to about 200 p.s.i.g. in a cracking furnace. Operating in this fashion, a conversion of 1,2-dihaloethane to vinyl halide of from about 60 to about 90 weight percent is achieved. The vinyl halide is separated from the hydrogen halide by quench and distillation. Uncracked dihaloethane is recycled back to the furnace.

'In the following examples ethane, hydrogen halide, halogen and air (or oxygen) were fed into the bottom of a vertically elongated reaction vessel precharged with a fluidizable catalyst. The catalyst compositions are in weight percent, based on the total weight of catalyst and support. The Weight percent of the rare earth halides catalyst component (including cerium halide and didymium halide) is calculated on the basis of its hydrated form, although during use, it is not necessarily fully or even partially hydrated.

6 sults therefor are indicated to be between 0.5 and 2 weight percent.

EXAMPLE XII The preceding examples are repeated so that each example includes runs which difier with regard to use of manganese chloride, calcium chloride, zinc chloride or titanium chloride, each in the following concentrations (in weight percent, based on the total weight of catalyst and support): 0.01, 1, 5, 10, 20. Manganese chloride performs best, with calcium chloride being better than either zinc chloride or titanium chloride; optimum results for both manganese chloride and calcium chloride are indicated to be between 1 and 10 weight percent.

EXAMPLE XIII The preceding examples are repeated so that each example includes runs at the following temperatures: 300 C., 350 C., 650 C. and 700 C. Optimum results are indicated to be between 350 C. and 650 C.

EXAMPLE XIV The preceding examples are repeated so that each example includes runs which difier with regard to use of the Example I II III IV V VI VII Molar feed ratio: Ethane] HCl/airICh/otheru 1/1/3. /0, 50/1. 85 n 1/1/3. 25/0. 50/1. 85 1/1/1.9/0.5 1/1/1.9/0.5 e 1/1/1. 9/0. 5/0. 77 1/1/2.06/0.5 b 1/1/1. 9/0. 5/0. 77 Catalyst composition (wt.

percent):

OuCl 0. 0. 30 0. 30 0.30 0. 30 0. 30 0. 30 Rare earth Cl (hydrated). 10.0 10. 0 10. 0 10. 0 10.0 10.0 10.0 LiCl 0. 06 0. 06 0. 06 0.06 0.06 0. 06 0. 06 Catalyst support Alumina Alumina Alumina Alumina Alumina Alumina Alumina Temperature C.) 500 525 525 550 560 525 550 Pressure (atnr) l 1 1 1 1 1 Ethane conversion (percent) 9t 0 91. 0 80. 1 66. 7 75. 3 78. 0 57. 8 Ethylene yield (percent) 69. 3 73. 5 80. 2 67. 6 82. 9 82.2 86. 5

l Nitrogen. b Argon.

EXAMPLE VIII The preceding examples are repeated so that each example includes runs which diifer with regard to use of the following copper chloride or iron chloride (substituted for copper chloride) concentrations (in weight percent, based on the total weight of catalyst and support): 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 1.0, 5.0, 10.0 Optimum results are indicated. to be between 0.25 and 0.35 weight percent for copper chloride and 0.3 to 0.4 weight percent for iron chloride.

EXAMPLE 1X The preceding examples are repeated so that each example includes runs which differ in the use of the following iron chloride concentrations where copper chloride is already employed or copper chloride where iron chloride is already employed (in weight percent based on the total weight of catalyst and support): 1, 3, 5, 7, 10.

EXAMPLE X The preceding examples are repeated so that each example includes runs which differ with regard to use of cerium chloride, didymium chloride, or rare earth chlorides extracted from monazite without removal of cerium or thorium, each in the following concentrations (in weight percent, based on the total weight of support and hydrated catalyst): 0.01, 0.1, 1, 5, 10, 15, 20, 25. Cerium chloride performs best, and optimum results therefor are indicated to be between 5 and 15 weight percent.

EXAMPLE XI The preceding examples are repeated so that each example includes runs which differ with regard to use of lithium chloride, sodium chloride, potassium chloride, rubidium chloride or cesium chloride, each in the following concentrations (in weight percent, based on the total weight of catalyst and support): 0.01, 0.05, 0.1, 0.5, 1, 2, 5, 10. Lithium chloride performs best, and optimum refollowing catalyst supports: sand, diatomaceous earth, alumina, silica gel, pumice, bauxite, or chromia-alumina. Chromia-alumina performs best, with alumina and silica gel being better than the other supports.

EXAMPLE XV The preceding examples are repeated so that each example includes runs which difier with regard to the following pressures (in atmospheres): 2, 5, 10, 13, 15, 20, 30.

EXAMPLE XVI The preceding examples are repeated so that each example includes runs which diifer with regard to the use of pure oxygen or air as a component of the feed stream.

EXAMPLE XVII The preceding examples are repeated so that each exam ple includes runs which differ with respect to the chlorine component of the feed molar ratio which is, respectively: 0.005, 0.01, 0.05, 0.1, 0.2, 0.5, 1.0.

EXAMPLE XVIII The preceding examples are repeated, first, changing the hydrogen chloride to hydrogen bromide and the meta] chlorides to metal bromide and, second, changing the hydrogen chloride to hydrogen iodide and the metal chlorides 7 to metal iodides. Good results are experienced except with Example XVII-I.

EXAMPLE XX The product mixtures from the preceding examples (except Example XVIII) are passed into the bottom of a vertically elongated reactor containing a copper halide catalyst supported on alumina. Oxygen is also admitted to the reactor. The catalyst is fluidized by a reactant flow rate of 0.5 foot per second at a reaction temperature of 300 C. and 150 p.s.i.g. to establish a contact time of 5 seconds.

EXAMPLE XXI The product mixtures from Example XX are passed into a cracking furnace at a temperature of 450 C. and 100 p.s.i.g. The product of vinyl halide, hydrogen halide and unreacted dihaloethane from the furnace is quenched and distilled, the unreacted dihaloethane is recycled to the furnace, the hydrogen halide is recycled to the oxydehydrogenation processes respectively set forth in the preceding examples (except Example XVIII), and the vinyl halide is recovered as product.

While the catalytic mixtures of this invention can be deposited upon the fluidized solid support in a number of different ways, a very simple and highly preferred methd of impregnating the support is to dissolve in water or an alcohol a weighed amount of the components of the catalyst mixture. A weighed amount of the support is then added to the water or alcohol and the contents stirred until completely homogenous. The water or alcohol is then evaporated at low temperature from the so-formed slurry. The evaporation is conveniently done by drying at a low temperature, e.g. about 100 C., in a low temperature air circulating oven. The dry impregnated support remaining can then be employed in the process of this invention.

I claim:

1. A process for the production of ethylene which comprises contacting ethane, at an elevated temperature and pressure with (l) a mixture consisting essentially of halogen, hydrogen-halide, and oxygen, and with (2) a fluidized catalyst which consists essentially of rare earth halide, an inert catalyst support and a compound selected from the group consisting of copper halide and iron halide.

2. The process of claim 1 wherein a diluent selected from the group consisting of nitrogen, helium and carbon dioxide is employed with said halogen.

3. The process of claim 1 wherein said fluidized catalyst additionally contains a compound selected from the group consisting of calcium halides and manganese halides in a concentration of from about 1 to about 10 percent by weight based on the total weight of catalyst and support.

4. The process of claim 1 wherein said fluidized catalyst contains copper halide and from about 1 to about 10 weight percent of iron halide based on the total weight of catalyst and support.

5. The process of claim 1 wherein said fluidized catalyst contains iron halide and from about 1 to about 10 weight precent copper halide based on the total weight of catalyst and support.

6. The process of claim 1 wherein said catalyst includes an alkali metal halide.

7. The process of claim 6 wherein said alkali metal halide is lithium halide.

' 8. The process of claim 1 wherein said fluidized catalyst additionally contains an alkali metal halide in a concentration of from about 0.01 percent to about 5 percent by weight based on the total weight of catalyst and support.

9. The process of claim 1 wherein said compound selected from the group consisting of copper halide and iron halide is in a concentration of from about 0.15 to about 3.0 weight percent, based on the total weight of catalyst and support.

10. The process of claim 1 wherein said compound selected from the group consisting of copper halide and iron halide is in a concentration of from about 0.15 to about 3.0 Weight percent based on the total weight of catalyst and support and the ratio of the concentration of rare earth halide to said compound is greater than 1:1.

11. The process of claim 1 wherein the catalyst sup port is selected from the group consisting of silica gel, alumina, and chromia-alumina.

12. The process of claim 1 wherein said rare earth halide is cerium halide.

13. The process of claim 1 wherein for every mole of ethane there are from about 0.5 to 2 moles of hydrogen halide, from about 0.5 to about 5 moles of air and from about 0.1 to about 1 mole of halogen.

14. The process of claim 1 wherein the reaction occurs at a temperature of from about 400 C. to about 650 C. and at a pressure of from about one atmosphere to about 30 atmospheres.

15. The process of claim 1 wherein said compound is copper halide in a concentration of from about 0.15 to about 3.0 weight percent, the Weight percent being based on the total weight of catalyst and support, and wherein the rare earth halide is a cerium halide, and the weight ratio of the concentration of cerium halide to said copper halide is greater than 1:1.

16. In a process for the oxydehydrogenation of ethane to ethylene by contacting an oxydehydrogenation feed consisting essentially of ethane, hydrogen halide and oxygen with a fluidized catalyst, the improvement therein, wherein the fluidized catalyst consists essentially of about 0.15 to about 3.0 percent copper halide or iron halide, from about 5 percent to about 20 percent rare earth halide, from about 0.01 percent to about 5 percent of an alkali metal halide, and inert catalyst support, all percentages being by weight based upon the total weight of catalyst and support and wherein the oxydehydrogenation feed additionally contains a halogen.

References Cited UNITED STATES PATENTS 3,542,895 11/1970 Russell 260-6833 3,483,136 12/1969 Vander Plas et al. 25244l 3,496,242 2/1970 Berkovitz et al 260-664 3,542,897 ll/1970 Wattimena et al. 260683.3 3,558,735 l/197l Beard 260-6833 3,250,280 9/1965 Wattimena et al. 260--68O DELBERT E. GANTZ, Primary Examiner G. E. SCHMITKONS, Assistant Examiner US. Cl. X.R.

252442, 462; 260656 R, 662 A, 677 XA 

